Lab Assignment: Firewalls
The following requirements must be met in order to set up this lab:
• Virtual Machine from previous labs (Ubuntu Linux 14.04 VM)
• ssh if using Linux, or Putty if you are using Windows as the host operating system.
• Internet access for adding packages to the install of Ubuntu
Logging In to VM
1. When Ubuntu starts, LightDM will show normal-user selected. Type in the password you used during the installation and press .
2. Type +, which will bring up the "Run Command" menu. Type in "gnome-terminal" and press . You can also select the terminal if it was attached to the Launcher panel.
3. This will load up a terminal to run commands with. With the terminal open, the operating system will need to be updated before continuing (even since you completed Lab 2). Type in the following to update and install security patches for Ubuntu:
sudo apt-get update && sudo apt-get -y dist-upgrade
(You will be prompted to type in your password)
4. Once the update is complete, click the gear in the top right corner and select "Shut down" and then select "Restart" to reboot the system.
Configuring the Firewall on Ubuntu
1. To make configuring of the firewall easier on Ubuntu, run the following commands to install gufw and openssh-server:
sudo apt-get install -y gufw openssh-server
2. With the host operating system (Linux or Windows), verify you can connect with SSH or Putty.
3. In the terminal, type ifconfig to find the IP address of your virtual machine.
4. In your host operating system, verify with a web browser that you can still reach your virtual machine by typing in the IP address of the virtual machine (that you discovered in the previous step) in the address box and that the "It works!" text appears in the webpage. If the page does not appear, run the following to start Apache and enable it to start by default:
sudo service apache2 start
sudo update-rc.d apache2 defaults
5. Return to the Linux terminal and type sudo gufw which will start the Firewall GUI. Click "Unlock," if necessary, to allow for changes. Once this is running, you can proceed to the Lab 4 Assignment.
Lab Assignment
You should now have an OpenSSH server and an HTTP server running on the Ubuntu host.
• For Status, change it to "on" and click the "+" on the bottom left of the GUI. Click "Application" under "Preconfigured" to select "SSH" which will change the last value to "SSH." Click "Add" and click "Close." Try to connect with a web browser.
• Select all of the rules in the Firewall GUI and select "-" to remove them. Click the "+" and change the service to "HTTP". Click "Add" and click "Close." Try to connect with a web browser.
• Click the "+" on the bottom left of the GUI and change the service to "SSH." Click "Add" and click "Close." Try to connect with a web browser.
• With these rules in place, open a terminal and run the following commands:
sudo iptables -vnL | grep dpt:22
sudo iptables -vnL | grep dpt:80
• In the Firewall GUI, edit the "80/tcp" rules to "deny" by clicking on the rule and clicking on the edit icon below it (the sun icon next to the plus and minus icons), changing the "Policy" to "Deny" and clicking "Apply." Then run the same commands.
For the lab report, you should have some form of output from these four procedures.
Lab Questions
1. Lab Question 1
What are the drawbacks of using a GUI to configure a firewall such as iptables (Hint: the output from iptables -vnL)?
2. Lab Question 2
What are some issues that may occur with using the "gufw" GUI to configure iptables using the "Preconfigured Services" in this lab?
3. Lab Question 3
What could be done differently to make these firewall rules even more secure?